Garmin Edge 500 w/ gsc10

insinkerator

So i finally hooked up my gsc10 onto my bike, got it to pair with my Edge, happy as larry. Off I went, happily monitoring my cadence, had a look at my speed, and it seemed a tad higher than normal ( was showing ~40km/h, where I would normally do 33-35km/h). Not sure if I was just pushing it harder than normal or what, so I fiddled around, and realised that garmin had autoset the circumference of the wheel.

I assumed this is what was causing the issue, and since I didn't know the circumference of my wheel offhand, I simply took off the speed sensor magnet. About 35km later, I noticed that my speed readings were very erratic, and four times, my garmin just actually dropped my speed readings altogether and I had to turn it off and on again. Has anyone had this happen? I've updated the firmware (2.3, now 2.4) and I'll try tomorrow or Saturday with the wheel circumference dialled in. It still shouldn't do what i'm describing though, right?

Thanks in advance

CheGuedara

Well the GSC-10 should give you more accurate speed info than the satellite alone and so may be reporting a higher speed for this reason (or you may have had a good bike day/tailwind with you

That said you might go back to the wheel size set it at any figure, back out of the menu and go back in and set it to automatic, at the start of the next ride (with wheel magnet attached) if should recalculate the diameter correctly for you. If that doesn't help it's possible that the battery in the GSC-10 is drained (if you've left it for a length of time near to the crank/spoke magnet either in the box or on the bike it is very easy to find it ganked by the time you come back to it) - the reading drop out sounds a lot like that. My first guess is the wheel diameter setting is incorrect however with the battery as a secondary issue.

Beasty

The 500 will use the GPS as default unless it's switched off. Any wheel circumference setting will be irrelevant in the circumstances

Redmond101

Starting to really doubt these garmin 500, every other day there seems to be a thread with an issue with either dropped signal, erratic reading or poor quality heart rate monitor! Think I'll invest my money elsewhere and stick with the cateye for the moment

Beasty

Never had a problem with either of mine. Most issues tend to be resolved when people work out how to use it properly;)

ratracer

Beasty wrote: »

Never had a problem with either of mine. Most issues tend to be resolved when people work out how to use it properly;)

I've never had any of these problems with mine, I think it's prob the best training gadget I've bought. I have noticed a few issues with the Garmin connect website when trying to get reports from it lately tho

Plastik

Mine has been flawless ... until the last two rides whereupon it has turned mental. Tuesday the gradient readings were off the wall and tonight there was a problem with the speed. I downloaded an update for it over the weekend, so something in that may be causing the problem ... I hope.

Inquitus

Beasty wrote: »

The 500 will use the GPS as default unless it's switched off. Any wheel circumference setting will be irrelevant in the circumstances

The Garmin uses the sensor as default if it is detected as it is more accurate than using gps for a live speed reading.

Leroy42

I do notice that sometimes the 500 readings does go a bit hayware, the other day I was apparently riding up a gradient of 950%!!

But I always find that once I download it it has sorted out these issues.

I think in particular the gradient etc is based on GPS and is therefore open to odd readings from time to time. Tree cover, weather conditions etc all can have an impact.

Overall, I think the 500 is a brilliant piece of kit, but just like any other piece of technology I don't slavishly follow the readings. Ride what is in front of you, as fast as you feel you should be going, and let the computer take care of itself.

insinkerator

Thanks for all the replies. I have been using the Garmin since last Summer with absolutely no issue. Has been an absolutely flawless piece of kit, and probably the best thing I've bought (bar my bike :pac:)

Inquitus wrote: »

The Garmin uses the sensor as default if it is detected as it is more accurate than using gps for a live speed reading.

What I'm wondering is, if the Garmin picks up the cadence/speed unit, so tries to take speed readings from the unit, but I have removed the spoke magnet, could that cause the symptoms I'm having?

Inquitus

insinkerator wrote: »

Thanks for all the replies. I have been using the Garmin since last Summer with absolutely no issue. Has been an absolutely flawless piece of kit, and probably the best thing I've bought (bar my bike :pac:)




What I'm wondering is, if the Garmin picks up the cadence/speed unit, so tries to take speed readings from the unit, but I have removed the spoke magnet, could that cause the symptoms I'm having?

I use my Garmin on my MTB without the sensor and on my roadbike with the sensor. I find the live speed reading can fluctuate quite a bit on the MTB when I am at a constant pace, perhaps as much as +-30%, esp if there is tree cover etc.

On the road bike the only time I have issues with the speed read out from the sensor is if the gap between magnet and sensor is more than a couple of mm. I have never tried to use the sensor without the magnet. Is the gap between magnet and sensor too wide on yours?

When you use the Garmin for the first few times with the sensor I guess it uses the number of wheel rotations compared to the gps speed to determine what diameter wheels you have and then uses that to calculate your speed from your sensor. It is possible if the gap between sensor and magnet is too large it is getting this calc wrong causing bad readings.

insinkerator

Well, the reset button flashes everytime, so I don't think it's too far....

I'll set up with a proper wheel circumference tomorrow and see how I get on. It's a shame because the cadence measuring worked a charm, but the speed was fluctuating like 2km/h at a time, which it has never done till today.

Thanks for the help

insinkerator

Set the correct wheel circumference, and took her out today. Speed seemed right, and no jumps, no dropping readings. So basically, if you have the gsc10 set up for cadence and speed, but remove the speed magnet, speed readings go crazy!

doozerie

I initially used my Garmin (705) for a few weeks without a cadence sensor. When I installed the cadence sensor, on my first ride the display went a bit mad and showed either silly readings or no readings at all (I can't quite remember which) for speed and heart rate. After a few minutes on the move it all started working correctly again. I reckoned that the unit was so busy doing the auto wheel circumference calculations for the first time that it wasn't able to do anything else such as measure heart rate, GPS location, etc. I imagine it doesn't have a very powerful processor in it and is therefore limited in what it can do all at the same time.

Perhaps the 500 is similar and because it is detecting your cadence sensor it's throwing everything at repeatedly trying and failing (due to absence of magnet) to measure your wheel circumference when set to auto, and therefore doesn't have enough resources left to reliably or accurately calculate and display your heart rate and GPS-derived speed.